Device for projecting symbols on a light-sensitive recording carrier



Sept. 10, 1968 R. v. TEGHOLM 3,401,399 DEVICE FOR PROJECTING SYMBOLS ON A LIGHT-SENSITIVE RECORDING CARRIER Filed March 31, 1967 I l 4 47 J l l United States Patent 3,401,399 DEVICE FOR PROJECTIN G SYMBOLS ON A LIGHT- SENSITIVE RECORDING CARRIER Ruben Valdemar Tegholm, Johanneshov, Sweden, as-

signor to Svenska Diamantbergborrnings Aktiebolaget, Sundbyberg, Sweden, a joint-stock company of Sweden Filed Mar. 31, 1967, Ser. No. 627,419 Claims priority, application Sweden, Apr. 1, 1966, 4,435 66 3 Claims. (Cl. 346-107) ABSTRACT OF THE DISCLOSURE A device for converting electrical signals to corresponding symbols which may be recorded on for example a self-developing recording paper. Two rods of conductive material and having rectangular cross sections are placed side'by side in a box-like envelope which has a rectangular cross section and is open at one end. A space is left between the rods and the envelope as well as between the rods themselves. The electrical signals are caused to generate spark discharges in the spaces and the light emanating from the spaces is utilized for recording the symbols.

Background of the invention The present invention relates to a device for projecting symbols, particularly digit symbols, on a light-sensitive recording carrier, which preferably may consist of a selfdeveloping ultra-violet sensitive paper.

It is already known to arrange display panels of different kinds where digit symbols are reproduced by a selective activation of one or several elongated light sources arranged in a predetermined pattern. Usually the pattern consists of two rectangles, one placed on top of the other, whereby a symbol is obtained which appears somewhat angular but nevertheless is sufficiently recognizable.

The object of the present invention is to provide a device which makes it possible to transform electrical signals to corresponding symbols recorded on a lightsensitive recording carrier, the symbols preferably being digit symbols.

According to the invention this is realized by means of a device comprising two rods each having a substantially rectangular end surface, whereby the rods are arranged side by side in such a way that their end surfaces will be situated essentially in one and the same plane and with a space left between one edge of one rod and one edge of the other rod whereby the rods further are partly enclosed in the casing open or transparent at one of its ends and having a substantially rectangular cross section, said end surfaces of the rods being situated essentially in the same plane with the opening in the casing and with spaces left between the outer edges of the rods and the inner edges of the opening, whereby each space is provided with an electrode situated some distance inwardly in the casing, which electrodes are arranged to be supplied with control voltages causing an electric spark discharge to take place at predetermined times and lighting up one or more of the spaces in such a way that if the casing is placed adjacent to a light-sensitive recording carrier, the light will result in a recording on the carrier in a pattern corresponding to the lighted up spaces.

The invention will be further described with reference to the accompanying drawings in which FIG. 1 shows in perspective and partly in section a device according to the invention, FIG. 2 is a considerably simplified schematic illustration of the control devices for the apparatus according to the invention, FIG. 3 is a schematic illustration of a voltage pulse generating circuit for generating a control voltage to be fed to one of the electrodes of the Cir device, and FIG. 4 shows a recording made by a device according to the invention. 7

FIG. 1 shows a device for projecting signs, for exam? ple digits on a light-sensitive recording carrier, for example self-developing ultra-violet sensitive paper.

The device shown comprises a box-like casing 1 pref erably manufactured from an isolating material in which an upper, shorter rod-like body 2 manufactured from a conducting material and having a rectangular cross section and a similar lower longer rod-like body 3 having a rectangular cross section are arranged in such a way that a space is defined between two adjacent edges of the respective bodies as well as between the outer edges of the bodies and the inner surfaces of the casing 1. This can for example be obtained by means of six rods, cams or the like 4 which may be arranged at the longitudinal edges of the bodies 2 and 3 as shown in FIG. 1. Apart from acting as spacing elements the rods 4 also act as light screens as will be further described below. The opening may also be covered by a transparent plate 20 made from for example plastic or glass.

Thus, there are obtained seven from each other distant spaces, namely one upper vertical left space a, one lower vertical left space b, one upper horizontal space 0, one upper right vertical space d, one middle horizontal space e, one lower horizontal space 1, and one vertical lower right space g.

Seven electrodes A, B, C, D, E, F and G are arranged through the walls of the casing in such a way that to each space corresponds one electrode, whereby the end surfaces of the electrodes, for example the end surface 5 of the electrode G, is situated at a suitable distance from the side of the body cooperating with the electrode in such a way that the spark gap 6 is obtained between the electrode and the body.

The bodies 2 and 3 may preferably be grounded. The rear part of the body 3 may for example be provided with a threaded bore which may serve as a fastener for the unit. It should be noted that the reason for the body 2 to be shorter than the body 3 is to make it possible to obtain a discharge also in the space 2 by providing an electrode E behind the body 2 having its end surface at a suitable distance from the body 3 so that thus a spark gap is obtained.

In FIG. 4 is shown how a recording made by the device according to the invention might look on a self-developing ultra-violet sensitive paper. The recording consists of the digit 4 where the parts a, b, e' and d correspond to the spaces or slots a, b, d and e. The recording has been made when the paper was in front of the device by supplying the electrodes A, B, D and E with a high voltage pulse having a magnitude of 1-10, preferably 2 kv., whereby a spark discharge was obtained between the electrodes and the grounded bodies 2 and 3 in such a way that the spaces were lighted up and an intensive light was projected on the paper.

In FIG. 2 is shown how a group of input lines 7 one for each of the different symbols, in the embodiment shown to digits 0 to 9, which are to be recorded are arranged as input lines to a coding device, for example a diode matrix 8 in such a way that the output lines 9 of the matrix, which are designated A, B' G, and which correspond to the spaces in the device are being supplied with a voltage corresponding to the kind of symbol which is to be recorded.

In the example which was related above when the digit 4 was to be recorded that input line 7 which corresponds to the digit 4 is connected with the output lines 9 in such a way that those output lines which correspond to the electrode A, B, E and D are activated. Each one of the lines 10 are provided with an amplifier 10 arranged to supply the electrodescorrespondingto the output line 9 witha high voltage pulse.

FIG. 3 shows schematically how such an amplifier 10 may be arranged. The amplifier is provided with two input terminals 11 and 12 one of which is connected to any of the output terminals 9 and the other to a suitable synchronizing voltages. The input voltages are chosen in such a way that the'collector of the transistor 13 will draw current whenboth input terminals 11 and 12 are activated and thus activate the thyristor 14. The capacitor 15 which is charged from a positive voltage source over the resistor 16 will thereby suddenly discharge over a primary winding 17 of the transformer T and on the output winding 18 of the transformer a sudden voltage pulse 'will occur. The output terminal 19 is connected to one of the electrodes A-E.

As stated previously the opening of the casing 1 may be covered by a transparent plate 20. his thus possible to seal the casing and fill it with a suitable gas e.g. for reducing electrode erosion or obtaining a glow discharge.

What is claimed is: p i

1. A device for projecting symbols, particularly digit symbols on a light-sensitive recording carrier, said device comprising two rods (2, 3) each having an essentially rectangular end surface, which rods are arranged in a spaced relationship to each other in such a way that their said end surfaces will be situated essentially in the same plane and with a spacing (e) between one edge of the end surface of one rod and one edge of the end surface of the adjacent rod, said rods further being partly enclosed in a casing (1) open or transparent at one of its ends and having an essentially rectangular cross section, said end surfaces of the rods being situated essentially in a plane with the opening in the casing whereby between the outer edges of said end surfaces and the edges of the opening in the casing further spaces (a, b, c, d, f and g) are left and that each one Qfsaid spaces is provided with a corresponding electrode (A, B, C, D, E, F and G) situated some distance into the casing and arranged to be selectively provided with activating voltages at predetermined instances and thereby generate an electric discharge causing one or more of the spaces (for example a, b, e, d) to be illuminatedso that if the casing (1) is placed adjacent to a light-sensitive recording carrier the light will cause a symbol to be recorded on the carrier having a pattern corresponding to the illuminated spaces.

2. Device according to claim 1, wherein the casing is constituted of an electrical non-conducting material and the electrodes are arranged through the walls of the easing, the rods (2', 3) 'are constituted of an electrically conductive material and the electric discharge comprises a short spark discharge between the respective electrode and a side surface of one of the rods situated adjacent the electrode.

3. Device according to claim 1, wherein the spaces are separated from each other and the rods are held in place in the casing by means of longitudinal spacing elernents (4).

References Cited UNITED STATES PATENTS 3,147,469 9/ 1964 Buchsbaum 340-324 X 3,196,445 7/1965 Trolio 346107 X 3,308,452 3/1967 Michel et al. 340-324 RICHARD B. WILKINSON, Primary Examiner.

JOSEPH W. HARTARY, Assistant Examiner. 

